Even though most of the studies were performed with the circulating isoform of fibronectin, which lacks both EDA and EDB and is called plasma fibronectin (pFN), studies using isoform-specific knockouts lacking either EDA, EDB, or both domains found that these two isoforms contribute to vasculogenesis in embryos and angiogenesis in cancer [4–7]. This evidence concerns the gene FN1 and cancer.